No Heat (won't ignite gas) Rheem Criterion II

[TonyG]

I've searched the groups for heating issues with the Criterion II and only found people having issues AFTER the heat came on. I'm having an issue with the unit before the heat comes on. The pre-purge runs for

30 seconds, I hear a single click sound, then several seconds later the fan turns on with the gas. Not being an hvac person, it seemed like the click was reminiscent of a bbq with an electric ignitor but it didn't make sense with the gas coming on several seconds later... After what I could gather on here, I still have a few questions. My first question is: What is the name of the long, round single wire that is bent 90 degrees and comes up in front of the gas? And, what is the name of the part that also sits in front of the gas and is shaped like an M made from square shaped metal? I'm guessing that the M shaped sensor is the flame sensor and that the single wire is the ignitor, correct? How would a properly running ignitor function? Is it supposed to click a spark like a bbq or is it supposed to get red hot? Any help I could get on this would be greatly appreciated.

Pardon the inexperience, we all have to start somewhere and I don't have a manual! Tony

[TonyG]

I've searched the groups for heating issues with the Criterion II and only found people having issues AFTER the heat came on. I'm having an issue with the unit before the heat comes on. The pre-purge runs for

30 seconds, I hear a single click sound, then several seconds later the fan turns on with the gas. Not being an hvac person, it seemed like the click was reminiscent of a bbq with an electric ignitor but it didn't make sense with the gas coming on several seconds later... After what I could gather on here, I still have a few questions. My first question is: What is the name of the long, round single wire that is bent 90 degrees and comes up in front of the gas? And, what is the name of the part that also sits in front of the gas and is shaped like an M made from square shaped metal? I'm guessing that the M shaped sensor is the flame sensor and that the single wire is the ignitor, correct? How would a properly running ignitor function? Is it supposed to click a spark like a bbq or is it supposed to get red hot? Any help I could get on this would be greatly appreciated.

Pardon the inexperience, we all have to start somewhere and I don't have a manual! Tony

[RP]

The M shaped thingy is called a hot surface ignitor (HSI)--it glows white hot for 30 seconds before the gas valve opens, and for a few seconds after. The L shaped thingy is the flame rod (or flame sensor), which in turn detects the presence of a burner flame via the rectification of AC current to DC current, which rectified current is in turn sensed by the control board or module.

hvacrmedic

[TonyG]

Thanks for the heads up! I turned the heat on and kept an eye on the HSI. It did not heat up. I then retested the heater with a voltmeter in place of the HSI and the system was sending electricity to the HSI so I'm guessing that's the issue :) I removed the HSI and it appears that one of the legs of it is cracked, actually looks scorched as well. Thanks again for the help, I truly appreciate it.

Tony

[TonyG]

Thanks for the heads up! I turned the heat on and kept an eye on the HSI. It did not heat up. I then retested the heater with a voltmeter in place of the HSI and the system was sending electricity to the HSI so I guess I found the issue :) Thanks again for the help, I truly appreciate it.

Tony

[TonyG]

Thanks for the heads up! I turned the heat on and kept an eye on the HSI. It did not heat up. I then retested the heater with a voltmeter in place of the HSI and the system was sending electricity to the HSI so I guess I found the issue :) After removing the HSI I noticed that it has a crack in one of the legs (looks scorched as well) Thanks again for the help, I truly appreciate it.

Tony

[TonyG]

Thanks for the heads up! I turned the heat on and kept an eye on the HSI. It did not heat up. I then retested the heater with a voltmeter in place of the HSI and the system was sending electricity to the HSI so I guess I found the issue :) After removing the HSI I noticed that it has a crack in one of the legs (looks scorched as well) Thanks again for the help, I truly appreciate it.

Tony

[RP]

Now I'll look into my crystal ball and make a wild guess that your furnace is somewhere between 10 and 12 years old? At least that's the norm for HSI failure. Typically the furnace will be due for replacement before the replacement HSI goes out.

hvacrmedic

[TonyG]

I'm sure the furnace is at least that old. Unfortunately, I rent the place so there aren't any upgrades in my future. In fact, I fix most everything around the house with my own cash so they won't raise the rent on me! lol

Tony

[TonyG]

I really have no idea how old it is, but I would side with you. We rent the place so there aren't any plans to put a new one in soon if you know what I mean...

[TonyG]

I really have no idea how old it is, but I would side with you. We rent the place so there aren't any plans to put a new one in soon if you know what I mean...

Tony

[RP]

If you're renting, then you especially shouldn't be messing with it. It's nice that you found the problem, but let the landlord hire a tech to repair it-- he might turn up some other problems, perhaps serious, that you can't see.

hvacrmedic

[buffalobill]

look in online catalog for parts

also photos and repair info i found on this website:

[Davey K]

replying to TonyG, Davey K wrote: My wife fixed ours. It would stop working seemingly out of nowhere, then it would turn on in the middle of the day. From our guess, the furnace was too cold (our furnace is located in the garage). We put a space heater in there and it turned on. Hope this helps!

[trader_4]

Well, that's a new one. A furnace that needs a heater to make it work. Do they charge extra for that feature?

[Vic Smith]

I have the same furnace (Rheem Criterion II.) For 7-8 years I had the same issues. Had to frequently clean the flame sensor to get it going. Seemed the colder it was, the more I had to fool with it. Of course it ran more often when it was cold. But I remember the first time it didn't start was a very cold day just a few months after it was installed. I was pissed. Then about 9 years ago the fan relay - main fan - on the control board failed. So I had the control board replaced. It's been running perfectly since - haven't had to touch it. I suspect the control board had a heat-related fault from the getgo. My basement is pretty cold. Similar to an issue I had with the ECU on my '88 Chevy Celebrity. It would fail intermittently from heat, killing the engine. I took the car to my mechanic and they used it for errands for a week, plugged into a portable ECU analyser. Never burped. The problem was I took it in late October on a day the weather turned cold. The mechanic didn't charge me, just said he'd get me in the spring. First warm day in the spring it failed. Had to tow it in to him, and he got me. Good mechanic. Anyway, heat affecting electronics isn't that rare an event. Since it cost me about 450 bucks to have that furnace control board replaced, that space heater may be a good option.

[micky]

I had a similar problem when my air conditioning didn't work. I had to put that outside part in a refrigerator, and now it's fine.